Kare worked for many years at Lawrence Livermore National Laboratory. In 1996, he left LLNL and, after working briefly for a small space-related startup company, in 1997 became an independent consultant specializing in advanced space system design, and started his own company.
Laser propulsion
He was a leading advocate of laser propulsion for space launch and in-space propulsion. He organized a 1986 workshop on laser propulsion at LLNL and later led a development program for ground to orbit laser launch supported by SDIO. He received a NASA Institute for Advanced Concepts grant to study a near-term form of laser launch using arrays of relatively low-powered lasers. He co-founded LaserMotive, Inc., a laser power beaming entrant in the, in 2006, and led the overall system design and the laser transmitter design efforts.
Sailbeam
Kare initially presented the concept of a SailBeam Boosted Magsail in a report prepared for NASA's Institute for Advanced Concepts called "High-Acceleration Micro-Scale Laser Sails for Interstellar Propulsion". A key idea is that if vast numbers of tiny sails are used to accelerate rather than one enormous one, the same amount of mass can be brought to high speeds with a less complex optical system. Unlike particle-beam propulsion, in which the beam disperses as it travels, a stream of low-mass microsails is not limited by such diffraction. By using dielectric rather than metal sails, the sails can also be accelerated much closer to their power source. The stream of microsails then becomes a source of propulsion to a starship as particle beams mounted on the starship vaporize the incoming sails into plasma.
Kare was also known as a science fiction fan and filksinger. He was a regular attendee and program participant at science fiction conventions starting in 1975. He was an editor of The Westerfilk Collection: Songs of Fantasy and Science Fiction, an important filksong collection, and later a partner in Off Centaur Publications, the first commercial publisher specializing in filk songbooks and recordings. Kare won two Pegasus Awards for his filk songs, Best Classic Filk Song in 2010 for "Fire in the Sky" and Best Writer/Composer in 2017, as well as seven additional nominations from 1987 onwards. An astrophysicist character with his name appears in War of Honor and Torch of Freedom, military science fiction novels in the Honor Harrington series by David Weber. A physicist by his name appear in Callahan's Touch by Spider Robinson, where he shoots a cluricaune with a fire extinguisher. His song "Fire in the Sky" is featured in the novelFallen Angels by Larry Niven, Jerry Pournelle, and Michael Flynn.